Thin film forming method and thin film forming appartus

ABSTRACT

A thin film forming method for forming a thin film on a workpiece accommodated within a reaction chamber includes a first operation of supplying a first source gas and a second source gas into the reaction chamber, and a second operation of stopping the supply of the first source gas, supplying the second source gas into the reaction chamber and setting an internal pressure of the reaction chamber higher than an internal pressure of the reaction chamber set in the first operation. The first operation and the second operation are alternately repeated a plurality of times.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of Japanese Patent Application No.2012-275271, filed on Dec. 18, 2012, and Japanese Patent Application No.2013-215719, filed on Oct. 16, 2013, in the Japan Patent Office, thedisclosure of which is incorporated herein in their entirety byreference.

TECHNICAL FIELD

The present disclosure relates to a thin film forming method and a thinfilm forming apparatus.

BACKGROUND

In the related art, LP-CVD (Low Pressure Chemical Vapor Deposition) isused in forming a film such as a silicon oxide film or the like. In thefilm formation using the LP-CVD, a film having a desired thickness isformed by supplying a gas, the flow rate of which is adjusted to aconstant value, into a pressure-controlled reaction chamber for apredetermined time.

In recent years, the structural change or miniaturization of asemiconductor device poses a problem in that the conventional processcannot be directly applied because the coverage performance is low underthe conventional LP-CVD film forming conditions. This problem isparticularly true when film formation is performed with respect to apattern of a STI (Shallow Trench Isolation) shape or a hole shape whichhas a high aspect ratio. In the LP-CVD film formation, there is a demandfor the reduction of an impurity concentration in a film. Thus, a demandhas existed for a method of forming a thin film having good properties.

SUMMARY

The present disclosure includes a thin film forming method and a thinfilm forming apparatus capable forming a thin film having goodproperties.

Furthermore, some embodiments of the thin film forming method and thinfilm forming apparatus are capable of forming a thin film having goodcoverage performance.

Moreover, some embodiments of the thin film forming method and thin filmforming apparatus are capable of forming a thin film having a reducedimpurity concentration.

According to one embodiment of the present disclosure, there is provideda thin film forming method for forming a thin film on a workpieceaccommodated within a reaction chamber, including: a first operation ofsupplying a first source gas and a second source gas into the reactionchamber; and a second operation of stopping the supply of the firstsource gas, supplying the second source gas into the reaction chamberand setting an internal pressure of the reaction chamber higher than aninternal pressure of the reaction chamber set in the first operation andthe second operation being alternately repeated a plurality of times.

According to another embodiment of the present disclosure, there isprovided a thin film forming method for forming a thin film on aworkpiece accommodated within a reaction chamber, including: a firstoperation of supplying a film forming gas into the reaction chamber toform a thin film on the workpiece accommodated within the reactionchamber; and a modifying operation of supplying a modifying gas into thereaction chamber to modify the thin film formed on the workpiece, themodifying operation being performed after a thin film having a desiredthickness is formed on the workpiece by alternately repeating the firstoperation and the modifying operation a plurality of times or byrepeating the first operation a plurality of times.

According to yet another embodiment of the present disclosure, there isprovided a thin film forming apparatus for forming a thin film on aworkpiece accommodated within a reaction chamber, including: a firstsource gas supplying unit configured to supply a first source gas intothe reaction chamber; a second source gas supplying unit configured tosupply a second source gas into the reaction chamber; a pressurecontrolling unit configured to control an internal pressure of thereaction chamber; and a control unit configured to control individualparts of the apparatus, the control unit being configured to form a thinfilm on the workpiece by alternately performing, a plurality of times, afirst operation of supplying the first source gas and the second sourcegas into the reaction chamber by controlling the first source gassupplying unit and the second source gas supplying unit, and a secondoperation of stopping the supply of the first source gas by controllingthe first source gas supplying unit, supplying the second source gasinto the reaction chamber by controlling the second source gas supplyingunit, and setting the internal pressure of the reaction chamber higherthan an internal pressure of the reaction chamber set in the firstoperation by controlling the pressure controlling unit.

According to yet another embodiment of the present disclosure, there isprovided a thin film forming apparatus for forming a thin film on aworkpiece accommodated within a reaction chamber, including: a filmforming gas supplying unit configured to supply a film forming gas intothe reaction chamber; a modifying-gas supplying unit configured tosupply a modifying gas for modification of the thin film formed on theworkpiece into the reaction chamber; and a control unit configured tocontrol individual parts of the apparatus, the control unit beingconfigured to form a thin film on the workpiece by alternatelyperforming, a plurality of times, a first operation of, by controllingthe film forming gas supplying unit, supplying the film forming gas intothe reaction chamber to form the thin film on the workpiece accommodatedwithin the reaction chamber and a modifying operation of, by controllingthe modifying-gas supplying unit, supplying the modifying gas formodification of the thin film formed on the workpiece into the reactionchamber, or by performing the modifying operation after a thin filmhaving a desired thickness is formed on the workpiece by repeating thefirst operation a plurality of times.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of the specification, illustrate embodiments of the presentdisclosure, and together with the general description given above andthe detailed description of the embodiments given below, serve toexplain the principles of the present disclosure.

FIG. 1 is a view illustrating a heat treatment apparatus according to anembodiment of the present disclosure.

FIG. 2 is a view illustrating a configuration of a control unit of theheat treatment apparatus shown in FIG. 1.

FIG. 3 is a view illustrating a recipe for explaining a thin filmforming method according to an embodiment of the present disclosure.

FIG. 4 is a view illustrating another example of the recipe forexplaining the thin film forming method.

FIG. 5 is a view illustrating a further example of the recipe forexplaining the thin film forming method.

FIG. 6 is a view illustrating a still further example of the recipe forexplaining the thin film forming method.

FIG. 7 is a view illustrating a yet still further example of the recipefor explaining the thin film forming method.

FIG. 8 is a view illustrating an even yet still further example of therecipe for explaining the thin film forming method.

FIG. 9 is a view illustrating an additional even yet still furtherexample of the recipe for explaining the thin film forming method.

DETAILED DESCRIPTION

Reference will now be made in detail to various embodiments, examples ofwhich are illustrated in the accompanying drawings. In the followingdetailed description, numerous specific details are set forth in orderto provide a thorough understanding of the present disclosure. However,it will be apparent to one of ordinary skill in the art that the presentdisclosure may be practiced without these specific details. In otherinstances, well-known methods, procedures, systems, and components havenot been described in detail so as not to unnecessarily obscure aspectsof the various embodiments.

A thin film forming method and a thin film forming apparatus accordingto the present disclosure will now be described in detail. In thefollowing description, the present disclosure will be described bytaking, as an example, a case where a HTO (High Temperature Oxide) filmis formed. In the present embodiment, description will be made bytaking, as an example, a case where a batch-type vertical heat treatmentapparatus shown in FIG. 1 is used as the thin film forming apparatus.

As illustrated in FIG. 1, a heat treatment apparatus 1 includes asubstantially cylindrical reaction tube 2 (reaction chamber) whoselongitudinal direction is oriented in a vertical direction. The reactiontube 2 has a double tube structure including an inner tube 3 and aroofed outer tube 4 configured to cover the inner tube 3 and formed tohave a specified gap with respect to the inner tube 3. The inner tube 3and the outer tube 4 are made of a material superior in heat resistanceand corrosion resistance, e.g., quartz.

A manifold 5 formed into a tubular shape and made of stainless steel(SUS) is arranged below the outer tube 4. The manifold 5 is air-tightlyconnected to the lower end of the outer tube 4. The inner tube 3 issupported by a support ring 6 protruding from the inner wall of themanifold 5 and one-piece formed with the manifold 5.

A cover 7 is arranged below the manifold 5 and can be moved up and downby a boat elevator 8. If the cover 7 is moved up by the boat elevator 8,the lower portion (throat portion) of the manifold 5 is closed. If thecover 7 is moved down by the boat elevator 8, the lower portion (throatportion) of the manifold 5 is opened.

A wafer boat 9 made of, e.g., quartz, is placed on the cover 7. Thewafer boat 9 is configured to accommodate a plurality of workpieces,e.g., semiconductor wafers 10, with a specified gas left therebetween inthe vertical direction.

A heat insulating body 11 is installed around the reaction tube 2 so asto surround the reaction tube 2. Temperature-increasing heaters 12 eachformed of, e.g., a resistance heating element, are installed on theinner wall surface of the heat insulating body 11. The interior of thereaction tube 2 is heated to a predetermined temperature by thetemperature-increasing heaters 12. As a result, the semiconductor wafers10 are heated to predetermined temperature.

A plurality of process gas introduction pipes 13 is inserted through(connected to) the side surface of the manifold 5. Only one of theprocess gas introduction pipes 13 is shown in FIG. 1. The process gasintroduction pipes 13 are arranged to face the interior of the innertube 3. For example, as illustrated in FIG. 1, the process gasintroduction pipes 13 are inserted through the side surface of themanifold 5 at the lower side of the support ring 6 (at the lower side ofthe inner tube 3).

The process gas introduction pipes 13 are connected to a process gassupply source (not shown) through mass flow controllers (not shown).Thus, a desired amount of process gas is supplied from the process gassupply source into the reaction tube 2 through the process gasintroduction pipes 13. In the present embodiment, a HTO film is formed.Therefore, film forming gases (source gases) supplied from the processgas introduction pipes 13 are, e.g., a dichlorosilane (DCS) gas as asilicon source and a nitrous oxide (N₂O) gas as an oxidizing agent.

An exhaust port 14 for exhausting a gas existing within the reactiontube 2 is installed on the side surface of the manifold 5. The exhaustport 14 is installed more upward than the support ring 6 to communicatewith a space defined between the inner tube 3 and the outer tube 4within the reaction tube 2. An exhaust gas or the like generated withinthe inner tube 3 is exhausted to the exhaust port 14 through the spacedefined between the inner tube 3 and the outer tube 4.

A purge gas supply pipe 15 is inserted through the side surface of themanifold 5 at the lower side of the exhaust port 14. A purge gas supplysource (not shown) is connected to the purge gas supply pipe 15. Adesired amount of a purge gas, e.g., a nitrogen gas, is supplied fromthe purge gas supply source into the reaction tube 2 through the purgegas supply pipe 15.

An exhaust pipe 16 is air-tightly connected to the exhaust port 14. Avalve 17 and a vacuum pump 18 are installed in the exhaust pipe 16 inthe named order from the upstream side thereof. The valve 17 adjusts theopening degree of the exhaust pipe 16, thereby regulating the internalpressure of the reaction tube 2 to a predetermined pressure. Forexample, the orifice or conductance of the valve 17 is adjusted tobecome smaller, thereby increasing the internal pressure of the reactiontube 2. The valve 17 may be completely closed. Moreover, the internalpressure of the reaction tube 2 may be increased by increasing the flowrate of the process gas. The vacuum pump 18 exhausts the gas existingwithin the reaction tube 2 through the exhaust pipe 16 and regulates theinternal pressure of the reaction tube 2.

A trap (not shown), a scrubber (not shown) and the like are installed inthe exhaust pipe 16, whereby the exhaust gas exhausted from the reactiontube 2 is detoxified and then exhausted out of the heat treatmentapparatus 1.

The heat treatment apparatus 1 further includes a control unit 100configured to control the respective parts thereof. FIG. 2 illustratesthe configuration of the control unit 100. As illustrated in FIG. 2, anoperation panel 121, a temperature sensor (group) 122, a manometer(group) 123, a heater controller 124, a MFC (Mass Flow Controller)control unit 125, a valve control unit 126 and the like are connected tothe control unit 100.

The operation panel 121 is provided with a display screen and anoperation button. The operation panel 121 transfers an operator'soperation instruction to the control unit 100 and displays differentkinds of information coming from the control unit 100 on the displayscreen.

The temperature sensor (group) 122 measures the temperatures of therespective parts, e.g., the internal temperature of the reaction tube 2,the internal temperature of the process gas introduction pipes 13, theinternal temperature of the exhaust pipe 16, and notifies the measuredvalues to the control unit 100.

The manometer (group) 123 measures the pressures of the respectiveparts, e.g., the internal pressure of the reaction tube 2, the internalpressure of the process gas introduction pipes 13, the internal pressureof the exhaust pipe 16, and notifies the measured values to the controlunit 100.

The heater controller 124 is configured to independently control thetemperature-increasing heaters 12. Responsive to an instruction sentfrom the control unit 100, the heater controller 124 applies a currentto the temperature-increasing heaters 12 to generate heat. Furthermore,the heater controller 124 measures the power consumption of each of thetemperature-increasing heaters 12 and notifies the measured values tothe control unit 100.

The MFC control unit 125 controls mass flow controllers (not shown)installed in the process gas introduction pipes 13 and the purge gassupply pipe 15 so that the flow rate of the gas flowing through the massflow controllers can become equal to the flow rate instructed by thecontrol unit 100. The MFC control unit 125 measures the actual flow rateof the gas and notifies the measured value to the control unit 100.

The valve control unit 126 controls the opening degrees of the valvesarranged in the respective pipes so that the opening degrees can becomeequal to the values instructed by the control unit 100.

The control unit 100 includes a recipe storage unit 111, a ROM (ReadOnly Memory) 112, a RAM (Random Access Memory) 113, an I/O port(input/output port) 114, a CPU (Central Processing Unit) 115, and a bus116 configured to interconnect the recipe storage unit 111, the ROM 112,the RAM 113, the I/O port 114 and the CPU 115.

The recipe storage unit 111 stores a setup recipe and a plurality ofprocess recipes. At the time of manufacture of the heat treatmentapparatus 1, only the setup recipe is stored in the recipe storage unit111. The setup recipe is executed when generating thermal models and thelike corresponding to individual heat treatment apparatuses. The processrecipes are prepared in a corresponding relationship with the heattreatments (heat treatment processes) actually performed by a user. Theprocess recipes define, e.g., a change in the temperature of therespective parts, a change in the internal pressure of the reaction tube2, start and stop timings of supply of the process gas and a supplyamount of the process gas, which are to be used from the time of loadingthe semiconductor wafers 10 into the reaction tube 2 to the time ofunloading the processed semiconductor wafers 10.

The ROM 112 is composed of an EEPROM (Electrically Erasable ProgrammableRead Only Memory), a flash memory, a hard disc or the like. The ROM 112is a recording medium configured to store an operation program of theCPU 115 or the like. The RAM 113 serves as a work area of the CPU 115.

The I/O port 114 is connected to the operation panel 121, thetemperature sensor (group) 122, the manometer (group) 123, the heatercontroller 124, the MFC control unit 125, the valve control unit 126 andthe like. The I/O port 114 controls the input/output of data andsignals.

The CPU 115 serves as a central function of the control unit 100 andexecutes the control program stored in the ROM 112. Pursuant to theinstruction sent from the operation panel 121, the CPU 115 controls theoperation of the heat treatment apparatus 1 according to the recipes(process recipes) stored in the recipe storage unit 111. That is to say,the CPU 115 causes the temperature sensor (group) 122, the manometer(group) 123 and the MFC control unit 125 to measure the temperature,pressure and flow rate in the respective areas within the reaction tube2, the process gas introduction pipes 13 and the exhaust pipe 16. Basedon the measured data, the CPU 115 outputs control signals to the heatercontroller 124, the MFC control unit 125, the valve control unit 126 andthe like, thereby controlling the respective parts to follow the processrecipes. The bus 116 delivers information between the respective parts.

Next, description will be made on a thin film forming method performedusing the heat treatment apparatus 1 configured as above. In thefollowing description, the operations of the respective partsconstituting the heat treatment apparatus 1 are controlled by thecontrol unit 100 (the CPU 115). In the respective processes, theinternal temperature and pressure of the reaction tube 2 and the flowrate of the gas are set to follow, e.g., the recipe illustrated in FIG.3, by controlling the heater controller 124 (the temperature-increasingheaters 12), the MFC control unit 125, the valve control unit 126 andthe like with the control unit 100 (the CPU 115) as described above. Inthe present embodiment, as illustrated in FIG. 3, a method of forming asilicon oxide film (a HTO film) using DCS (dichlorosilane) as a siliconsource and using N₂O (nitrous oxide) as an oxidizing agent will bedescribed by way of example.

First of all, as shown in an item (a) of FIG. 3, the internaltemperature of the reaction tube 2 is set to be equal to a predeterminedtemperature, e.g., 600 degree C. As shown in an item (e) of FIG. 3, apredetermined amount of nitrogen is supplied from the purge gas supplypipe 15 into the inner tube 3 (the reaction tube 2). Subsequently, thewafer boat 9 which accommodates the semiconductor wafers 10 therein isplaced on the cover 7. Then, the cover 7 is moved up by the boatelevator 8 to load the semiconductor wafers 10 (the wafer boat 9) intothe reaction tube 2 (Loading Operation). Grooves and/or holes having aso-called STI structure are formed on the surfaces of the semiconductorwafers 10.

Subsequently, as shown in the item (e) of FIG. 3, a predetermined amountof nitrogen is supplied from the purge gas supply pipe 15 into the innertube 3. As indicated in the item (a) of FIG. 3, the internal temperatureof the reaction tube 2 is set to be equal to a predeterminedtemperature. The gas existing within the reaction tube 2 is exhausted todepressurize the interior of the reaction tube 2 to a predeterminedpressure as depicted in an item (b) of FIG. 3. At this time, theinternal temperature of the reaction tube 2 is set to be equal to, e.g.,800 degree C., and the internal pressure of the reaction tube 2 is setto be equal to, e.g., 0.1 Torr (13.3 Pa). Then, the interior of thereaction tube 2 is stabilized at this temperature and pressure(Stabilizing Operation).

After the interior of the reaction tube 2 is stabilized at thepredetermined pressure and temperature, as shown in an item (c) of FIG.3, a predetermined amount of a DCS gas as a first film forming gas (asource gas) is introduced from the process gas introduction pipes 13into the reaction tube 2. At this time, in the present embodiment, theDCS gas is supplied at a flow rate of 200 sccm as shown in the item (c)of FIG. 3. Simultaneously with the supply of the first film forming gas,a N₂O gas as a second film forming gas (a source gas) is supplied fromthe process gas introduction pipes 13 into the reaction tube 2 asindicated in an item (d) of FIG. 3. The N₂O gas is supplied at a flowrate of 200 sccm as shown in the item (d) of FIG. 3. At this time, theinternal pressure of the reaction tube 2 is kept at 0.1 Torr (13.3 Pa)as shown in the item (b) of FIG. 3 (First Operation). The firstoperation is maintained for a predetermined time, e.g., about 1 minute.

In this regard, when supplying the film forming gases in the firstoperation, it is preferred in some embodiments that the film forminggases are supplied into the reaction tube 2 at the predetermined flowrate by gradually increasing the flow rate of the film forming gases andnot by suddenly supplying the film forming gases into the reaction tube2 at the predetermined flow rate (200 sccm).

Subsequently, as shown in the item (c) of FIG. 3, the supply of the DCSgas as the first film forming gas is stopped and, as indicated in theitem (b) of FIG. 3, the internal pressure of the reaction tube 2 is sethigher than the pressure set in the first operation. For example, theinternal pressure of the reaction tube 2 is set to be equal to 0.1 Torrto 10 Torr (13.3 Pa to 1330 Pa). As shown in the item (d) of FIG. 3, thesupply of the N₂O gas as the second film forming gas is not stopped butis kept at a flow rate of 200 sccm (Second Operation). The secondoperation is maintained for a predetermined time, e.g., about 1 minute.

Subsequently, as shown in the items (b) and (c) of FIG. 3, the firstoperation is performed again in which the DCS gas as the first filmforming gas is supplied and in which the internal pressure of thereaction tube 2 is reduced. Moreover, the supply of the N₂O gas as thesecond film forming gas is maintained as indicated in the item (d) ofFIG. 3. In this operation, the flow rate of the first film forming gas,the flow rate of the second film forming gas, the internal pressure ofthe reaction tube 2 and the operation maintaining time are set to beequal to those of the first operation of the previous cycle.

Then, the second operation is performed again in which the supply of theDCS gas as the first film forming gas is stopped and in which theinternal pressure of the reaction tube 2 is increased as shown in theitem (b) of FIG. 3. Moreover, the supply of the N₂O gas is not stoppedbut is kept at a flow rate of 200 sccm as indicated in the item (d) ofFIG. 3. In this operation, the flow rate of the second film forming gas,the internal pressure of the reaction tube 2 and the operationmaintaining time are set to be equal to those of the second operation ofthe previous cycle.

In this way, a cycle including the first operation and the secondoperation is performed a predetermined number of times, thereby forminga HTO film having a predetermined thickness on each of the semiconductorwafers 10. The number of repetitions of the cycle in some embodimentsis, e.g., about 75 to 225. The number of repetitions of the cycle isdecided depending on the required film thickness or the like.

In the present embodiment, the supply and stop of the DCS gas as thefirst film forming gas is repeatedly performed. The supply of the N₂Ogas as the second film forming gas is maintained without regard to thesupply of the first film forming gas. The internal pressure of thereaction tube 2 is kept higher when the first film forming gas isstopped rather than when the first film forming gas is supplied. Sincethe internal pressure of the reaction tube 2 is lower in the firstoperation than in the second operation, it becomes easy to spread outthe DCS gas and the N₂O gas over the semiconductor wafers 10 havinggrooves and/or holes. Inasmuch as the N₂O gas is supplied at a higherpressure in the second operation than in the first operation, it ispossible to accelerate the reaction (oxidation) of the DCS gas and theN₂O gas which are spread out over the semiconductor wafers 10 havinggrooves and/or holes. This makes it possible to enhance the coverageperformance of the HTO film formed on each of the semiconductor wafers10.

If the HTO film having a predetermined thickness is formed, the supplyof the film forming gases from the process gas introduction pipes 13 isstopped. Then, the film forming gases are discharged from the interiorof the reaction tube 2. As shown in the item (e) of FIG. 3, apredetermined amount of nitrogen is supplied from the purge gas supplypipe 15 into the inner tube 3, thereby discharging the gases remainingwithin the reaction tube 2 (Purging Operation).

Subsequently, as shown in the item (a) of FIG. 3, the internaltemperature of the reaction tube 2 is set to be equal to a predeterminedtemperature, e.g., 600 degree C. The gases remaining within the reactiontube 2 are discharged and the reaction tube 2 is returned to normalpressure. Then, the cover 7 is moved down by the boat elevator 8,thereby unloading the semiconductor wafers 10 (the wafer boat 9) fromthe interior of the reaction tube 2 (Unloading Operation). Thus, theformation of a laminated film is finished.

The present disclosure is not limited to the aforementioned embodimentbut may be modified or applied in many different forms. In theaforementioned embodiment, a configuration in which the flow rates ofthe film forming gases (the DCS gas and the N₂O gas) are equally set inthe respective cycles is taken as an example. However, for example, asillustrated in FIG. 4, the flow rates of the film forming gases may bedifferently set depending on the cycle. In addition, the flow rates ofthe DCS gas and the N₂O gas may be differently set in the respectivecycles.

In the aforementioned embodiment, a configuration in which the flowrates of the film forming gases (the DCS gas and the N₂O gas) areequally set in the first operation and the second operation is taken asan example. However, for example, the flow rates of the film forminggases in the first operation may be set different from the flow rates ofthe film forming gases in the second operation. Moreover, the secondoperation may be set longer than the first operation in such a way thatthe first operation maintaining time becomes equal to 1 minute and thesecond operation maintaining time becomes equal to 2 minutes.Conversely, the first operation may be set longer than the secondoperation.

In the present disclosure, it is preferred in some embodiments that theinternal pressure (P2 or P4) of the reaction tube 2 in the secondoperation is set higher than the internal pressure (P1 or P3) of thereaction tube 2 in the first operation. The internal pressure of thereaction tube 2 may be differently set depending on the cycle. Forexample, as illustrated in FIG. 5, cycle A may be performed a pluralityof times and, then, cycle B may be performed a plurality of times. Inthis case, it is preferred that the internal pressure P3 of the reactiontube 2 in the first operation of cycle B is set higher than the internalpressure P1 of the reaction tube 2 in the first operation of cycle A(P3>P1). This is because it is possible to enhance the coverageperformance and the deposition rate. In addition, the internal pressureP2 or P4 of the reaction tube 2 in the second operation may be changedto a great extent. For example, the internal pressure P4 of the reactiontube 2 in the second operation of cycle B may be set significantlyhigher than the internal pressure P2 of the reaction tube 2 in thesecond operation of cycle A (P4>>P2). In the aforementioned embodiment,description has been made by taking, as an example, a case where theinternal temperature of the reaction tube 2 is set to be equal to 800degree C. However, the internal temperature of the reaction tube 2 maybe appropriately changed.

In the aforementioned embodiment, the present disclosure has beendescribed by taking, as an example, a case where the DCS gas is used asthe silicon source, i.e., the first film forming gas, and where the N₂Ogas as the oxidizing agent is used as the second film forming gas.However, other materials may be used as long as the materials arecapable of forming a HTO film (a SiO₂ film). For example,tetrachlorosilane, trichlorosilane or hexachlorodisilane (HCD) may beused as the silicon source. Nitrogen oxide (NO), nitrogen dioxide (NO₂)or ozone (O₃) may be used as the oxidizing agent. A SiN film may beformed in place of the HTO film.

As illustrated in FIG. 6, after the first operation and the secondoperation, it may be possible to perform a modifying operation in whichmodifying gases, e.g., oxygen (O₂) and hydrogen (H₂), are supplied fromthe process gas introduction pipes 13 into the reaction tube 2 togenerate active species (radicals) containing oxygen within the reactiontube 2. The modifying gases are not limited to hydrogen (H₂) and oxygen(O₂) but may be any gas that can modify the HTO film. For example, themodifying gases may be hydrogen (H₂) and nitrous oxide (N₂O). Themodifying operation is performed for a predetermined time, e.g., 1 to 60seconds, preferably 5 to 15 seconds. In the modifying operation, theformed thin film (the HTO film) and the activated oxygen and hydrogen(radicals) react with each other, which makes it possible to reduce theconcentration of impurities such as chlorine (Cl), hydrogen (H), carbon(C), nitrogen (N) and the like contained in the HTO film. For example,the concentration of chlorine in the formed HTO film was measured. As aresult, it was confirmed that the concentration of chlorine in the HTOfilm can be significantly reduced by performing the modifying operation.It was also confirmed that the film stress of the HTO film can be madelarger. In particular, it was confirmed that the film stress in a Y-axisdirection can be increased approximately four times.

In the modifying operation, it is preferred in some embodiments that theinternal temperature of the reaction tube 2 is set to be equal to 700degree C. to 900 degree C. This is because, by setting the internaltemperature of the reaction tube 2 to fall within this range, it becomeseasy to remove impurities such as chlorine, hydrogen and the likecontained in the HTO film and easy to modify the HTO film. Particularly,in the modifying operation, it is preferred in some embodiments that theinternal temperature of the reaction tube 2 is set to be equal to aboutthe HTO film forming temperature (800 degree C.), e.g., 750 degree C. to850 degree C. This is because, by setting the internal temperature ofthe reaction tube 2 to fall within this range, it becomes possible toeasily control the internal temperature of the reaction tube 2.

In the modifying operation, it is preferred in some embodiments that theinternal pressure of the reaction tube 2 is set to be equal to 1.33 Pato 133 Pa (0.01 Torr to 1 Torr). This is because, by setting theinternal pressure of the reaction tube 2 to fall within this range, itbecomes easy to remove impurities such as chlorine, hydrogen and thelike contained in the HTO film and easy to modify the HTO film. Inparticular, it is preferred in some embodiments that the internalpressure of the reaction tube 2 is set to be equal to 6.65 Pa to 13.3 Pa(0.05 Torr to 0.1 Torr). This is because, by setting the internalpressure of the reaction tube 2 to fall within this range, it becomespossible to improve the interfacial uniformity of the formed HTO film.

In the modifying operation, the ratio of the supply amounts of hydrogen(H₂) and oxygen (O₂) is in some embodiments preferably 1:1 to 1:3, morepreferably 1:1.5 to 1:2. This is because, by setting the mixing ratio ofoxygen and hydrogen to fall within this range, it becomes possible toreduce the concentration of impurities contained in the HTO film and toincrease the film stress of the HTO film.

The modifying operation may not be performed in each and every cycle.For example, during the initial several cycles, the first operation andthe second operation may be performed without performing the modifyingoperation. Thereafter, the first operation, the second operation and themodifying operation may be performed. As illustrated in FIG. 7, themodifying operation may be performed after the HTO film having a desiredthickness is formed. In these cases, it is possible to reduce theconcentration of impurities contained in the HTO film and to increasethe film stress of the HTO film.

As illustrated in FIG. 8, the modifying operation may be performed inplace of the second operation. Even in this case, it is possible toreduce the concentration of impurities contained in the HTO film and toincrease the film stress of the HTO film. In this case, it is possibleto significantly reduce the concentration of chlorine in the HTO film.In particular, it was confirmed that the concentration reduction in thefilm depth direction is remarkable.

As illustrated in FIG. 9, the modifying operation may be performed afterthe HTO film having a desired thickness is formed by repeating the firstoperation a plurality of times. Even in this case, it is possible toreduce the concentration of impurities contained in the HTO film and toincrease the film stress of the HTO film.

In the aforementioned embodiment, the present disclosure has beendescribed by taking, as an example, a case where the batch-type verticalheat treatment apparatus having a double tube structure is used as thethin film forming apparatus. However, the present disclosure can beapplied to, e.g., a batch type heat treatment apparatus having a singletube structure.

The control unit 100 according to an embodiment of the presentdisclosure can be realized by an ordinary computer system withoutresorting to a dedicated system. For example, the control unit 100 forperforming the aforementioned processes can be formed by installing, ina general-purpose computer, the program downloaded from a recordingmedium (a flexible disc, a CD-ROM (Compact Disc-Read Only Memory) or thelike) which stores a program for performing the aforementionedprocesses.

An arbitrary means can be used to supply the program. In addition tosupplying the program through a specified recording medium, it may bepossible to supply the program through, e.g., a communication line, acommunication network, a communication system or the like. In this case,for example, the program may be posted to a BBS (Bulletin Board System)of a communication network and may be provided through a network in astate that the program overlaps with a carrier wave. Then, the programthus provided is started up and is executed under the control of an OS(Operating System) just like other application programs. This makes itpossible to perform the aforementioned processes.

The present disclosure is useful in a thin film forming method and athin film forming apparatus.

According to the present disclosure, it is possible to provide a thinfilm forming method and a thin film forming apparatus, which are capableof forming a thin film having good properties.

While certain embodiments have been described, these embodiments havebeen presented by way of example only, and are not intended to limit thescope of the disclosures. Indeed, the novel methods and apparatusesdescribed herein may be embodied in a variety of other forms.Furthermore, various omissions, substitutions and changes in the form ofthe embodiments described herein may be made without departing from thespirit of the disclosures. The accompanying claims and their equivalentsare intended to cover such forms or modifications as would fall withinthe scope and spirit of the disclosures.

1-11. (canceled)
 12. A thin film forming apparatus for forming a thinfilm on a workpiece accommodated within a reaction chamber, theapparatus comprising: a first source gas supplying unit configured tosupply a first source gas into the reaction chamber; a second source gassupplying unit configured to supply a second source gas into thereaction chamber; a pressure controlling unit configured to control aninternal pressure of the reaction chamber; and a control unit configuredto control individual parts of the apparatus, the control unit beingconfigured to form a thin film on the workpiece by alternatelyperforming, a plurality of times, a first operation of supplying thefirst source gas and the second source gas into the reaction chamber bycontrolling the first source gas supplying unit and the second sourcegas supplying unit, and a second operation of stopping the supply of thefirst source gas by controlling the first source gas supplying unit,supplying the second source gas into the reaction chamber by controllingthe second source gas supplying unit, and setting the internal pressureof the reaction chamber higher than an internal pressure of the reactionchamber set in the first operation by controlling the pressurecontrolling unit.
 13. The apparatus of claim 12, further comprising: amodifying-gas supplying unit configured to supply a modifying gas formodification of the thin film formed on the workpiece into the reactionchamber, wherein the control unit is configured to form a thin film onthe workpiece by repeating, a plurality of times, the first operation,the second operation and a modifying operation of, by controlling themodifying-gas supplying unit, supplying the modifying gas into thereaction chamber to modify the thin film formed on the workpiece. 14.The apparatus of claim 12, further comprising: a modifying-gas supplyingunit configured to supply a modifying gas for modification of the thinfilm formed on the workpiece into the reaction chamber, wherein thecontrol unit is configured to form a thin film on the workpiece byperforming a modifying operation of, by controlling the modifying-gassupplying unit, supplying the modifying gas into the reaction chamber tomodify the thin film formed on the workpiece, after a thin film having adesired thickness is formed on the workpiece by alternately repeatingthe first operation and the second operation a plurality of times. 15.The apparatus of claim 13, wherein the modifying gas includes oxygen andhydrogen.
 16. The apparatus of claim 12, wherein a groove or a hole isformed on the workpiece and the thin film is formed in the groove or thehole.
 17. The apparatus of claim 12, wherein the first source gascomprises dichlorosilane and the second source gas comprises nitrousoxide.
 18. A thin film forming apparatus for forming a thin film on aworkpiece accommodated within a reaction chamber, the apparatuscomprising: a film forming gas supplying unit configured to supply afilm forming gas into the reaction chamber; a modifying-gas supplyingunit configured to supply a modifying gas for modification of the thinfilm formed on the workpiece into the reaction chamber; and a controlunit configured to control individual parts of the apparatus, thecontrol unit being configured to form a thin film on the workpiece byalternately performing, a plurality of times, a first operation of, bycontrolling the film forming gas supplying unit, supplying the filmforming gas into the reaction chamber to form the thin film on theworkpiece accommodated within the reaction chamber and a modifyingoperation of, by controlling the modifying-gas supplying unit, supplyingthe modifying gas for modification of the thin film formed on theworkpiece into the reaction chamber, or by performing the modifyingoperation after a thin film having a desired thickness is formed on theworkpiece by repeating the first operation a plurality of times.